Michael D. Dukes, P.E.
Michael Dukes is an irrigation specialist, and he has produced numerous publications about agricultural irrigation over the last few years. However, this "focus" on more efficient use of irrigation water has led him to projects in many different areas. Dukes' overall subject is really water management, and his studies have an impact in several areas. First, agricultural producers in Florida use a lot of water, and if they can use it more efficiently, they save money. Also, Florida's water supplies are being challenged by a large population and extensive agricultural sector, so any area where water use can be reduced conserves this resource. There is also an important environmental impact, because water that is applied to agricultural fields picks up nutrients and carries them into Florida's groundwater, streams, and lakes.
Dukes explains the challenge that producers face with regard to their finances, trapped as they are between variations in rain, temperature, pests, and other natural forces, the costs of planting and growing a crop, and changes in market prices. Regardless of farmers' efforts, there is no guarantee that they will make money in any given year. That is one reason that producers continue to look to technological innovations that can help them trim their costs and better manage their crops. Anything Dukes can do to reduce the risks that producers face improves their odds of staying in business.
According to the U. S. Geological Service, Floridians use about 7 billion gallons of water a day. Over half of this water is used for agricultural irrigation. A much smaller but still significant fraction is used for urban irrigation. If Dukes' work can help to save a few percent in irrigation water use, that would represent enormous water savings across the state. Florida would seem to have plenty of water, but even during good times, managing the residential and industrial water needs of Florida's large and growing population is a complex task. Dukes cites a series of droughts from 2001 through 2008 that put significant strains on these supplies. Also, he says that even though Floridians have reduced their individual water use in some areas of the state, the continually increasing population means that more water is demanded than ever before.
Fertilizers often rely on the application of the right amount of water to move the fertilizer into the root zone where plants can utilize it, but too much water carries fertilizers into the ground water and reduces the effectiveness of fertilizer applications. Fertilizers cost money, and if they are washed away, that is literally money down the drain. Agricultural producers cannot control rain, but they can control their irrigation patterns and timing. Better control can mean more effective use of both water and fertilizers and, therefore, savings for both producers and the environment.
Fertilizers that are washed from agricultural fields end up in Florida's streams, rivers, and lakes, where growth of plants and algae is enhanced. With continual agricultural runoff, plants and algae can grow so much that they begin to starve water bodies of oxygen, light and other nutrients. Lakes are especially susceptible where slower growing plants and animals can die off, and the process of eutrophication, or lake death, begins. Irrigating more efficiently can in turn reduce runoff and lower the impact on the surrounding environment.
Dukes helps producers make their irrigation more efficient mainly through the use of "smart" controllers. In the recent past, many irrigation systems, even residential ones, have been run by timers. This is the most basic type of controller, but not the most efficient. Timers assure that plants get enough water, but they depend on human managers to function at their best. Timer-controllers can turn on the system regardless of whether water is needed, perhaps even while it is raining. Controllers are more efficient when rain sensors are added, which can prevent the system from running while it is raining or if it has recently rained.
When Dukes talks about "smart" controllers, he is talking about the next level of technology. Smart controllers monitor some aspect of the environment to determine when water is needed. One technology that Dukes has worked with extensively in recent years is the soil moisture sensor, or SMS, controller.
As its name says, the soil moisture sensor measures soil moisture directly, and so it takes into account several factors at once that affect how much water is available to plants. The SMS controller is sensitive to when it has rained recently, but it also takes into account how much of that moisture is lost when the temperature is high or the humidity is low. Dukes' research has confirmed that SMS controllers reduce residential water use without a loss of turf quality.
The SMS controller is one type of controller that takes a plant's point of view of water needs. Dukes has been working with another type of controller that takes this approach called evapotranspiration, or ET, controllers. "Evapotranspiration" is a combination of two words, evaporation and transpiration, which are two ways that plants and soil lose moisture. Evaporation is more familiar; it is simply water returning to the air as a gas. Transpiration is a more specialized word that refers to the process by which plants lose moisture through their pores. It could be compared to sweating, and plants use this process for cooling among other purposes. In whatever way plants lose moisture, that moisture must be replenished.
There are several kinds of ET controllers, but each one uses a different combination of data and sensors to estimate the evapotranspiration rate of plants and adjusts irrigation cycles accordingly. Usually, the controller is set up for a particular type of plant or crop, and they can combine historical data about how a particular crop uses water with real-time measurements of local weather conditions, either from sensors or weather stations.
Though Dukes' focus has been agricultural, increasingly he has had requests and opportunities to apply his expertise in urban settings. Developers throughout Florida are required to project water of their housing projects for many years into the futures. Many of these developers see residential irrigation as a place where they can show water conservation in their planning, and they look to engineers like Dukes for recommendations about the latest technology.
The emphasis on urban needs has drawn resources away from agriculture. Also, even though there are many job opportunities in agriculture, fewer students are choosing agriculture as a major and fewer still are choosing irrigation. Dukes observes that the need for irrigation specialists is as important as ever, and for those interested in water and resource management, irrigation is great place to start.
Dr. Dukes specializes in irrigation and drainage engineering; water quantity and quality issues; crop consumptive use/evapotranspiration; Best Management Practices to reduce nonpoint source pollution.
Research and Extension
- Ph.D North Carolina State University, Raleigh, N.C.
- M.C.E. University of Delaware, Newark, Delaware
- B.A.S. University of Delaware, Newark, Delaware
Interim Chair, Environmental Horticulture
Professor, UF Agricultural and Biological Engineering Department.
Director for the Center for Landscape Conservation and Ecology.
Associate Professor, UF Agricultural and Biological Engineering Department
Assistant Professor, UF Agricultural and Biological Engineering Department
Graduate Research Assistant, Biological and Agricultural Engineering Department, North Carolina State University
Graduate Teaching Instructor, Biological and Agricultural Engineering Department, North Carolina State University
Awards and Honors
- EPAF Wells Fargo Extension Professional and Enhancement Award 2013
- ASABE Young Extension Worker 2011
- UF Research Foundation Professorship 2010
- ASABE Blue Ribbon Award 2010
- ASABE Florida Section Young Engineer 2009
- Outstanding Service Award, ASABE Florida Section, 2007
- ASABE Outstanding Reviewer Award 2007
- Young Researcher Award 2005,ASABE Florida Section
- Member, Alpha Epsilon Honor Society
- Member, Phi Kappa Phi Honor Society
- Member, Gamma Sigma Delta Agricultural Honor Society
Other Professional Activities
- American Society of Agricultural & Biological Engineers
- National Society of Professional Engineers
- American Society of Civil Engineers, Environmental Water Resources Institute